It's the first PreCure series with space travel, aliens, rockets, etc. It's also not really up to much. I'd suggest skipping it. I don't hate the season and I'm happy that there are people who enjoy it, but its character writing is weak and I was drifting through its episodes without being grabbed. The second half of the series is a bit directionless and you might feel that the baddies are too easily forgiven.
It gets worthwhile in the forties. (Ep.40 onwards, roughly. It's so exact that I'm sure that's how they planned out the series. "This is where we'll stop pissing it away.") I still wouldn't call it "good", but episodes suddenly start to have a point and you'll no longer be semi-comatose.
The problem starts with the cast. They've got five PreCures again (rarely a good thing):
1. HOSHINA HIKARU, aka. CURE STAR = a generic Pink Leader. She's likeable, but there's nothing about her that's not a remix of earlier, better Pink Leaders. She also has an overused catchphrase ("kirayaba!"). Usually I didn't mind it, but there were times when it got on my nerves. The most interesting thing about Hikaru is her asymmetrical costume and giant hat "bells", making her resemble a jester.
I like her hostile grandad, but the show forgets about him in a few episodes.
2. HAGOROMO LALA, aka. CURE MILKY = an alien from the planet Saman. She has her moments, e.g. being grumpy in the very early episodes and having a rough time with Earthlings who mistrust aliens. Theoretically, she's the show's best character. She's the cause of several decent episodes and she has character points like being thunderstruck in ep.13 by everyone being able to do simple arithmetic. On Saman, AI does all that for you.
Usually, though, she's walking wallpaper. I've decided that she's actually the show's biggest failure. (I dislike Blue Cat more, but that character does what she was supposed to do.) Lala should have been one of the standout characters that helped to define the show in your mind, but she never really comes together. She feels like some bits and pieces that never coalesced into a complete character.
She also has a tag phrase ("lun"), although fortunately it's unobtrusive. In ep.13, they ENCOURAGE HER TO SAY IT. Bloody hell. Piss off.
3. AMAMIYA ELENA, aka. CURE SOLEIL = a sunny girl with an annoying family. Well, it's mostly her dad. She gets quite a good two-parter about her career plans (eps.42-43) and ended up being marginally my favourite of the Star Twinkle PreCures. She's still a non-presence most of the time, though.
4. KAGUYA MADOKA, aka. CURE SELENE = an enigmatic girl whose father hunts aliens for the government. This could have been meaty, in context, but it ends up dribbling away since this season isn't really interested in drama. She's easy to forget about.
5. YUNI, aka. BLUE CAT, aka. CURE COSMO = the dramatically meaningful one, but alas I disliked her a lot. She's a phantom space thief. She steals stuff. She's got a well-hidden reason to make her sympathetic, of course, but she's still a fairly cold, hostile character until she thaws into nothingness later in the series. She dresses like a gender-swapped Kaito Kid from Detective Conan. (I hate the Kaito Kid too.) The show's trying to have it both ways, with the character eventually being heroic while her iconography and actions say "master thief". "As Blue Cat, there's nothing I can't steal!"
In fairness, my reaction here is partly just my own prejudices. I'm not interested in anime with thief hero characters. I avoid Lupin III, for instance. In addition, though, Yuni is a cat girl who says "nyan", although mysteriously from many angles she seems to have mouse ears. Oh, and when she was stealing all those treasures... why? I don't get it. It can't have been to support her planet, because everyone there is frozen. Zero maintenance. The show's painting her as a Robin Hood who's robbing the rich to help the poor, but there's a disconnect between this and her tragic backstory.
The baddies are better. Eye One gets a meaningful character journey, although she's so bratty and self-centred that it occasionally doesn't have the weight it deserved. (e.g. ep.27.) I'm also irritated by her name's official transliteration. "Aiwarn". Yeah, right. (Darknest's commanders are based on Japanese mythology, with Kappard being a kappa and Tenjou being a tengu. Eye One is a hitotsume-kozou, i.e. a cyclops-child.) Garuouga is badass enough that in one episode it was annoying to see the girls calling their attacks in traditional magical girl fashion, because Garuouga's so fast and strong that it should have been impossible to win after giving him that much time.
That said, though, I'm underwhelmed by the baddies' opposition to this year's themes (tolerance and diversity). Kappard in particular keeps shouting his stupid catchphrase ("aliens can never understand each other") without ever giving the impression that he's internalised it or that it's intrinsic to the character. He's just saying it because it's an antagonist's job to oppose.
My favourite first-half episodes were the off-world ones, e.g. episodes 8, 10, 15 and 24. There's some cool SF in here. Ep.8, for instance, has comedy dog aliens who judge people on how much fur they have. It rains bones! As for Ep.10, that's downright educational. Water bears! Ep.34 is good in a similar way, as Earth is visited by a mute but intelligent alien cactus. This is capable of being far more alien than, say, Doctor Who. Animation can easily show planets with different gravity, for instance, but that's extremely rare in live-action TV SF.
Blue Cat wrecks some of those episodes by being in them, though.
Then there's J. J. Abrams. There's an American film director called "Abraham" who's secretly an alien and keeps covering up the girls' superhero fights, etc. by saying that he's shooting a film and it's all Hollywood magic. That was annoying too. It's too silly to be taken seriously, unless you're a small child.
Ep.44 even makes Santa annoying, thanks to his verbal tic. (He's an alien from Planet Santa.)
I object to the ease with which the girls shuttle between Earth and space. I had a similar problem with Mahoutsukai PreCure (which had the same series co-ordinator), which ended up regarding travel between two worlds as no harder than popping next door.
I don't like the theme songs and title sequences. The first ending has the kind of dancing that says you're knackered from a full set and you just want to rest. As for that first ending's song, Tomoko described it as sounding like "a 1980s idol group that didn't sell". (It's true that they're going for a 1980s vibe.)
When reviewing a PreCure series, I normally cite some standout episodes. Here, I won't. The level's too low. I don't think there's enough meat on the show for it to be worth bothering with. The nearest it gets to a genuinely good episode would be something like the whimsical alien worldbuilding of ep.10. On the downside, though, it's sometimes show-breakingly stupid, e.g. Blue Cat needing to be talked into co-operating in ep.21, the "I mustn't laugh" misunderstanding in ep.24, the student council selection silliness in ep.35 and casually forgiving genocide in ep.38.
There's yet more "you can't tell anyone you're a PreCure/alien/Earthling". Which can sod off.
What's more, this has a nadir in ep.30. The girls have just been accused of something absurd on a highly civilised planet. "Lala and her accomplices have stolen the princess's power and escaped!" Oh, good grief. In other words, the PreCures have been accused of stealing their own powers. They could have trumped all this by revealing their secret identities, but of course we're told that it would be terrible if anyone found out that they were PreCures! Why? The answer is throwaway bullshit. Furthermore, fifteen minutes later the girls blow their cover by transforming in public, in front of everyone. There are no consequences. None of this is ever mentioned again.
Oh, and Blue Cat told everyone to run away from the police instead of, say, standing their ground and asking their accusers to produce even a shred of evidence. Just because you're a criminal, dear, that doesn't mean everyone else should make themselves look guilty for no reason.
Ep.31 is supposed to be a huge episode... but it's not. It's a big step up, admittedly, but it's a mid-season finale without much weight. Garuouga shows up and trashes the PreCures. Hikaru loses a fight... and I realised that I hadn't been expecting much from her in the first place. Meanwhile, Fuwa turns into a My Little Pony.
In short, there's very little here. It's not openly contemptuous of the idea of drama, unlike KiraKira a la Mode, but it's also not noticeably committed to it. It's still PreCure, admittedly, and I can imagine a new viewer loving it. It's nice. It has laudable themes, despite the non-contribution to the debate from the strawman villains. There are some wonderful moments, e.g. Hikaru offering her hand to Kappard in ep.45. That's so PreCure. Nonetheless, I'd often be on the verge of falling asleep. My notes for ep.29 include "ZZZZ" and "Oh God, I'm struggling to keep watching. Please finish soon."
Until now, every PreCure series has had something distinctive. I can see reasons to watch them all, rather than one of the others, even if in some cases those are outweighed by reasons not to do so. KiraKira a la Mode is a waste of time, but not a complete one. Yukari and Akira are memorable. Here, though, the best I can do is superficial stuff like the setting. That barely counts. I can't find anything beyond peripheral, barrel-scraping reasons to go looking for this series. Blue Cat is undeniably distinctive and a new departure for this franchise, but for me she also was a reason to fast-forward. This is a kind, warm-hearted show, as always with PreCure, but the characters and plotting are both underwritten fluff. Otherwise... well, it's got spaceships and aliens. I do admittedly like the very occasional SF-heavy episodes.
That's all. There's nothing else.